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1,513 results on '"Ohshima, Hiroyuki"'

3. Electrophoretic mobility of a water-in-oil droplet separately affected by the net charge and surface charge density

Author

Uematsu, Yuki and Ohshima, Hiroyuki

Subjects
Condensed Matter - Soft Condensed Matter, Physics - Chemical Physics, Physics - Fluid Dynamics
Abstract

Water-in-oil emulsions and droplets exhibit completely different physico-chemical properties compared to oil-in-water emulsions and droplets. Thus, directly applying a standard theoretical model to water-in-oil systems cannot describe these anomalous properties. Here, the electrophoretic mobility of a water-in-oil droplet is analytically investigated using Debye-H\"uckel linearization and neglecting Marangoni effect. The resulting electrophoretic mobility is shown to be separately dependent on the net charge of the droplet and the surface charge density at the droplet interface. Furthermore, when the net charge is negligible, electrophoretic mobility is proportional to the surface charge density with a negative coefficient. This indicates that the internal electric double layer inversely contributes the electrophoresis. This theory is applied to experimental data of water-in-oil emulsions and droplets in the literature, and qualitative and quantitative verification of the theory is discussed., Comment: 11 pages, accepted version

Published
2023
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5. Improvement of User Interface of Blind Football Play-by-Play System for Visually Impaired Spectators-Tangible Sports

Author

Ohshima, Hiroyuki, Kobayashi, Makoto, Shimada, Shigenobu, Filipe, Joaquim, Editorial Board Member, Ghosh, Ashish, Editorial Board Member, Prates, Raquel Oliveira, Editorial Board Member, Zhou, Lizhu, Editorial Board Member, Stephanidis, Constantine, editor, Antona, Margherita, editor, Ntoa, Stavroula, editor, and Salvendy, Gavriel, editor

Published
2023
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26. A New Method for Calculating the Hamaker Constant Based on the Hansen Solubility Parameters for Non-Polar Liquids.

Author

Ohshima, Hiroyuki and Takeda, Shin-ichi

Subjects
SOLUBILITY, LIQUIDS, NUMERICAL calculations, DATABASES, PERMITTIVITY
Abstract

A simple relationship between the Hamaker constant and the Hansen solubility parameters for non-polar liquids is derived by combining a Hamaker constant/surface tension relationship derived by Israelachvili and a Hansen solubility parameters/surface tension relationship derived by Abbott. With this relationship, one can easily estimate the Hamaker constant of non-polar liquids on the basis of the database of the Hansen solubility parameters. This is an entirely new method for calculating the Hamaker constant without recourse to data on the frequency-dependent dielectric permittivity of those substances (which are required for the rigorous Lifshitz theory) and laborious numerical calculations. [ABSTRACT FROM AUTHOR]

Published
2024
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40. Validation of the Hybrid Turbulence Model in Detailed Thermal-Hydraulic Analysis Code SPIRAL for Fuel Assembly Using Sodium Experiments Data of 37-Pin Bundles

Author

Yoshikawa, Ryuji, Imai, Yasutomo, Kikuchi, Norihiro, Tanaka, Masaaki, and Ohshima, Hiroyuki

Abstract

AbstractIn the study of safety enhancements on advanced sodium-cooled fast reactors (SFRs) by the Japan Atomic Energy Agency (JAEA), it has been essential to clarify the thermal hydraulics under various operating conditions at high and low flow rate conditions in a fuel assembly (FA) with wire-wrapped fuel pins to assess the structural integrity of the fuel pin that achieves a high-performance core with high burnup ratio and high power density. A finite element thermal-hydraulic analysis code named SPIRAL has been developed by JAEA to analyze the detailed thermal-hydraulic phenomena in the FA of a SFR.In this study, numerical simulations of 37-pin bundle sodium experiments at different Reynolds (Re) number conditions, including a transitional condition between laminar and turbulent flows and turbulent flow conditions, were performed to validate the developed hybrid k-ε/kθ-εθturbulence model equipped in SPIRAL to consider the low Re number effect near the wall in the flow and temperature fields. The temperature distributions predicted by SPIRAL were consistent with those measured in the sodium experiments at the Re number conditions. Through the validation study, the applicability of the hybrid turbulence model in SPIRAL to the thermal-hydraulic evaluation of sodium-cooled FAs in a wide range of Re numbers was confirmed.

Published
2024
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